Daoud Brikci, Hichem 
  
The MCE (MultiCriteria Evaluation) process combine the criteria into a single decision image called "suitability map" 
(in the sense that it shows varying degrees of suitability for the objective under question) in the form of a weighted 
and linear combination (Voogd, 1983): 
Chis 
my, i.e., S = Swi; , where: S=suitability, x; =criterion score of factor i; and w; =weight of factor i (see fig.2). 
This procedure is not unfamiliar in GIS and has a form very similar to the nature of a regression equation. 
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
‘the 
d is 
ads 
Category 1 
Category 2 
es [1 Category 3 
Es Figure 2. IDRISI approach results. 
n 
y 3.2 Electre Approach 
pe Using ELECTRE Tri method we do not have to 
9 standardise the factor maps. However, the 
image illustrating the soils should be in a re 
quantitative scale (see fig.3). Ee ee 0 T 
ELECTRE Tri builds an outranking relation S, i.e., an pU RR T | 
validates or invalidates the assertion aSb, (and b,Sa), : i 
e iW. us " immature Aluvia 1 7 727 nz sd i 
whose meaning is "a is at least as good as b,"; where deposited ri 
F denote the set of the indices of the criteria g; g», ..., : ; 
gn (F={1,2, .., m}) and B the set of indices of the glk (————— 
profiles defining p--/ categories (B1, 2, ..., p}), b, 0. 1 2 34 5 BT 89 m 
being the upper limit of category C; and the lower : : ; ; 
mit of category Cr: Ae 2 o pre tble D Figure 3. An example of soil scale quantification. 
ng 
) a 
1at Scale b; b; 
Habitation | -4234.67/0 (m) |-1500, -200 
road -3471.31/0 (m) | -800 | -200 
od well -3832.75/0 (m) |-1000| -500 
fa hydrography | -3429.65/0 (m) | -600 | -300 
Ice Slope -32 / 0 (96) 0 | 4 
Dt Soil 0-1-5-6-7-9 44 | +6 
  
  
  
  
  
  
Table. Profiles evaluations. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 309